Gleasons to Mexico c. 1860's

I received this request from Mexico in Spanish from a young man, Clemente Gleason Galicia, trying to learn of his Gleason ancestry - English or Irish.

"...of our great-grandfather we did no longer know anything, will these data give you some idea? , or does he/she know about somebody that emigrated toward Mexico, calculating toward 1860-1880?? this date calculating the age of my grandparents." [perhaps marrying the surname Alvarez - AlG].